Blood For Blood

You or a willing humanoid creature acts as the host of this spell for the entire duration. The host's vitality can be drained in order to restore the vitality of another. 

As a bonus action, the host can expend a pool of d6s equal to 1 + the original caster's spellcasting modifier. The amount rolled damages the host and in turn heals a creature they can see within 30 feet. The spell ends should the original caster lose concentration or should the host fall unconscious.

For every 2 levels that this spell is upcast, an additional host can be selected, for a maximum of 3 hosts.

Additionally, casting this spell at 5th level or higher converts excess healing into temporary hit points.